public Hashids(string salt = "", int minHashLength = MIN_HASH_LENGTH, string alphabet = DEFAULT_ALPHABET)
{
if (string.IsNullOrWhiteSpace(alphabet))
{
throw new ArgumentNullException("alphabet");
}
if (alphabet.Contains(' '))
{
throw new ArgumentException("alphabet cannot contain spaces", "alphabet");
}
Alphabet = new String(alphabet.Distinct().ToArray());
Salt = salt;
MinHashLength = minHashLength;
// separators should be in the alphabet
Separators = DEFAULT_SEPARATORS;
Separators = new String(Separators.Where(x => Alphabet.Contains(x)).ToArray());
if (string.IsNullOrWhiteSpace(Separators))
{
throw new ArgumentException("alphabet does not contain separators", "separators");
}
Separators = ConsistentShuffle(input: Separators, salt: Salt);
// remove separator characters from the alphabet
Alphabet = new String(Alphabet.Where(x => !Separators.Contains(x)).ToArray());
if (string.IsNullOrWhiteSpace(Alphabet) || Alphabet.Length < MIN_ALPHABET_LENGTH)
{
throw new ArgumentException("alphabet must contain atleast " + MIN_ALPHABET_LENGTH + " unique, non-separator characters.", "alphabet");
}
double sepDivisor = 3.5;
if ((Separators.Length == 0) || (((double)Alphabet.Length / (double)Separators.Length) > sepDivisor))
{
int sepsLength = (int)Math.Ceiling(Alphabet.Length / sepDivisor);
if (sepsLength == 1)
{
sepsLength++;
}
if (sepsLength > Separators.Length)
{
int diff = sepsLength - Separators.Length;
Separators += Alphabet.Substring(0, diff);
Alphabet = Alphabet.Substring(diff);
}
else
{
Separators = Separators.Substring(0, sepsLength);
}
}
double guardDivisor = 12.0;
Alphabet = ConsistentShuffle(input: Alphabet, salt: Salt);
int guardCount = (int)Math.Ceiling(Alphabet.Length / guardDivisor);
if (Alphabet.Length < 3)
{
Guards = Separators.Substring(0, guardCount);
Separators = Separators.Substring(guardCount);
}
else
{
Guards = Alphabet.Substring(0, guardCount);
Alphabet = Alphabet.Substring(guardCount);
}
}